Texas Instruments
CY74FCT543ATQCT

The \x92FCT543T octal latched transceivers contain two sets of eight D-type latches with separate latch-enable (LEAB\, LEBA\) and output-enable (OEAB\, OEBA\) inputs for each set to permit independent control of input and output in either direction of data flow. For data flow from A to B, for example, the A-to-B enable (CEAB\) input must be low in order to enter data from A or to take data from B, as indicated in the function table. With CEAB\ low, a low signal on the A-to-B latch-enable (LEAB\) input makes the A-to-B latches transparent; a subsequent low-to-high transition of the LEAB\ signal puts the A latches in the storage mode and their outputs no longer change with the A inputs. With CEAB\ and OEAB\ low, the 3-state B-output buffers are active and reflect the data present at the output of the A latches. Control of data from B to A is similar, but uses CEBA\, LEBA\, and OEBA\ inputs.

These devices are fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs, preventing damaging current backflow through the device when it is powered down.